Figure 8. Hearing and diving can shape the ear structures. A, there is a slight correlation (P = 0.021) for terrestrial species of the bandwidth, number of octaves, and the length of the bony meatus. B, linear regression for the ratio of the average cross-section area size of the cochlea and low frequency cut-off in-air are highly significant for all specimens. C, cochlear height is a relevant factor for the high-frequency cut-off in aquatic animals. D, underwater low-frequency cut-off reveals correlation to the area size of the round window. Legend: filled circles = Pinnipedia + Ursidae, unfilled circles = Musteloidea + Canidae; green = terrestrial species, blue = aquatic + semi-aquatic species * = P ≤ 0.05, **** = P ≤ 0.0001.